1. Field of the Invention
This invention relates to reversible hammer mills and more particularly to such mills having provision for preventing dust issuing from the material feed inlet by restricting the fan effect of the mill rotor to one in which there is a downdraft through the mill regardless of rotor rotation.
2. Description of the Prior Art
The prior art relating to downdraft type mills includes the patents of Liggett U.S. Pat. Nos. 1,751,009 of Mar. 18, 1930 and West 2,767,929 of Oct. 23, 1956. In these two examples, there is provided means for preventing the escape of dust and fine material through the feed inlet. Such prevention is needed to force the fan effect of the mill rotor to create a "downdraft" in the mill casing. The prior art patent of Danyluke et al U.S. Pat. No. 3,083,921 of Apr. 2, 1963 is an example of dust prevention means applied to a reversible rotary impactor mill, which is intended to produce a negative air pressure at the delivery exit thereby developing a positive pressure at the inlet to allow for an updraft in the inlet.
Another prior art form of inhibiting the escape of dust through a mill feed inlet is seen in a Bulletin of the Pennyslvania Crusher Division, Bath Iron Works Corporation, West Chester, Pa., page 9, FIG. 13. The Bulletin bears the date 1041-62 (meaning 1962).